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linux/fs/sysfs/sysfs.h

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sysfs: make sysfs_dirent->s_element a union Make sd->s_element a union of sysfs_elem_{dir|symlink|attr|bin_attr} and rename it to s_elem. This is to achieve... * some level of type checking : changing symlink to point to sysfs_dirent instead of kobject is much safer and less painful now. * easier / standardized dereferencing * allow sysfs_elem_* to contain more than one entry Where possible, pointer is obtained by directly deferencing from sd instead of going through other entities. This reduces dependencies to dentry, inode and kobject. to_attr() and to_bin_attr() are unused now and removed. This is in preparation of object reference simplification. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:15 +00:00
struct sysfs_elem_dir {
struct kobject * kobj;
};
struct sysfs_elem_symlink {
sysfs: reimplement symlink using sysfs_dirent tree sysfs symlink is implemented by referencing dentry and kobject from sysfs_dirent - symlink entry references kobject, dentry is used to walk the tree. This complicates object lifetimes rules and is dangerous - for example, there is no way to tell to which module the target of a symlink belongs and referencing that kobject can make it linger after the module is gone. This patch reimplements symlink using only sysfs_dirent tree. sd for a symlink points and holds reference to the target sysfs_dirent and all walking is done using sysfs_dirent tree. Simpler and safer. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:15 +00:00
struct sysfs_dirent * target_sd;
sysfs: make sysfs_dirent->s_element a union Make sd->s_element a union of sysfs_elem_{dir|symlink|attr|bin_attr} and rename it to s_elem. This is to achieve... * some level of type checking : changing symlink to point to sysfs_dirent instead of kobject is much safer and less painful now. * easier / standardized dereferencing * allow sysfs_elem_* to contain more than one entry Where possible, pointer is obtained by directly deferencing from sd instead of going through other entities. This reduces dependencies to dentry, inode and kobject. to_attr() and to_bin_attr() are unused now and removed. This is in preparation of object reference simplification. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:15 +00:00
};
struct sysfs_elem_attr {
struct attribute * attr;
};
struct sysfs_elem_bin_attr {
struct bin_attribute * bin_attr;
};
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:16 +00:00
/*
* As long as s_count reference is held, the sysfs_dirent itself is
* accessible. Dereferencing s_elem or any other outer entity
* requires s_active reference.
*/
sysfs: move struct sysfs_dirent to private header struct sysfs_dirent is private to the fs/sysfs/ subtree. It is not even referenced as an opaque structure outside of that subtree. The following patch moves the declaration from include/linux/sysfs.h to fs/sysfs/sysfs.h, making it clearer that nothing else in the kernel dereferences it. I have been running this patch for years. Please integrate and forward upstream if there are no objections. From: "Adam J. Richter" <adam@yggdrasil.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-02-16 13:35:25 +00:00
struct sysfs_dirent {
atomic_t s_count;
sysfs: slim down sysfs_dirent->s_active Make sysfs_dirent->s_active an atomic_t instead of rwsem. This reduces the size of sysfs_dirent from 136 to 104 on 64bit and from 76 to 60 on 32bit with lock debugging turned off. With lock debugging turned on the reduction is much larger. s_active starts at zero and each active reference increments s_active. Putting a reference decrements s_active. Deactivation subtracts SD_DEACTIVATED_BIAS which is currently INT_MIN and assumed to be small enough to make s_active negative. If s_active is negative, sysfs_get() no longer grants new references. Deactivation succeeds immediately if there is no active user; otherwise, it waits using a completion for the last put. Due to the removal of lockdep tricks, this change makes things less trickier in release_sysfs_dirent(). As all the complexity is contained in three s_active functions, I think it's more readable this way. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:18 +00:00
atomic_t s_active;
sysfs: add sysfs_dirent->s_parent Add sysfs_dirent->s_parent. With this patch, each sd points to and holds a reference to its parent. This allows walking sysfs tree without referencing sd->s_dentry which can go away anytime if the user doesn't control when it's deleted. sd->s_parent is initialized and parent is referenced in sysfs_attach_dirent(). Reference to parent is released when the sd is released, so as long as reference to a sd is held, s_parent can be followed. dentry walk in sysfs_readdir() is convereted to s_parent walk. This will be used to reimplement symlink such that it uses only sysfs_dirent tree. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:14 +00:00
struct sysfs_dirent * s_parent;
sysfs: use singly-linked list for sysfs_dirent tree Make sysfs_dirent use singly linked list for its tree structure. sysfs_link_sibling() and sysfs_unlink_sibling() functions are added to handle simpler cases. It adds some complexity and cpu cycle overhead but reduced memory footprint is worthwhile on big machines. This change reduces the sizeof sysfs_dirent from 104 to 88 on 64bit and from 60 to 52 on 32bit. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:18 +00:00
struct sysfs_dirent * s_sibling;
struct sysfs_dirent * s_children;
sysfs: add sysfs_dirent->s_name Add s_name to sysfs_dirent. This is to further reduce dependency to the associated dentry. Name is copied for directories and symlinks but not for attributes. Where possible, name dereferences are converted to use sd->s_name. sysfs_symlink->link_name and sysfs_get_name() are unused now and removed. This change allows symlink to be implemented using sysfs_dirent tree proper, which is the last remaining dentry-dependent sysfs walk. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:15 +00:00
const char * s_name;
sysfs: make sysfs_dirent->s_element a union Make sd->s_element a union of sysfs_elem_{dir|symlink|attr|bin_attr} and rename it to s_elem. This is to achieve... * some level of type checking : changing symlink to point to sysfs_dirent instead of kobject is much safer and less painful now. * easier / standardized dereferencing * allow sysfs_elem_* to contain more than one entry Where possible, pointer is obtained by directly deferencing from sd instead of going through other entities. This reduces dependencies to dentry, inode and kobject. to_attr() and to_bin_attr() are unused now and removed. This is in preparation of object reference simplification. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:15 +00:00
union {
struct sysfs_elem_dir dir;
struct sysfs_elem_symlink symlink;
struct sysfs_elem_attr attr;
struct sysfs_elem_bin_attr bin_attr;
} s_elem;
sysfs: rename sysfs_dirent->s_type to s_flags and make room for flags Rename sysfs_dirent->s_type to s_flags, pack type into lower eight bits and reserve the rest for flags. sysfs_type() can used to access the type. All existing sd->s_type accesses are converted to use sysfs_type(). While at it, type test is changed to equality test instead of bit-and test where appropriate. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:21 +00:00
unsigned int s_flags;
sysfs: move struct sysfs_dirent to private header struct sysfs_dirent is private to the fs/sysfs/ subtree. It is not even referenced as an opaque structure outside of that subtree. The following patch moves the declaration from include/linux/sysfs.h to fs/sysfs/sysfs.h, making it clearer that nothing else in the kernel dereferences it. I have been running this patch for years. Please integrate and forward upstream if there are no objections. From: "Adam J. Richter" <adam@yggdrasil.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-02-16 13:35:25 +00:00
umode_t s_mode;
sysfs: store sysfs inode nrs in s_ino to avoid readdir oopses Backport of ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.22-rc1/2.6.22-rc1-mm1/broken-out/gregkh-driver-sysfs-allocate-inode-number-using-ida.patch For regular files in sysfs, sysfs_readdir wants to traverse sysfs_dirent->s_dentry->d_inode->i_ino to get to the inode number. But, the dentry can be reclaimed under memory pressure, and there is no synchronization with readdir. This patch follows Tejun's scheme of allocating and storing an inode number in the new s_ino member of a sysfs_dirent, when dirents are created, and retrieving it from there for readdir, so that the pointer chain doesn't have to be traversed. Tejun's upstream patch uses a new-ish "ida" allocator which brings along some extra complexity; this -stable patch has a brain-dead incrementing counter which does not guarantee uniqueness, but because sysfs doesn't hash inodes as iunique expects, uniqueness wasn't guaranteed today anyway. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-11 05:02:45 +00:00
ino_t s_ino;
sysfs: move struct sysfs_dirent to private header struct sysfs_dirent is private to the fs/sysfs/ subtree. It is not even referenced as an opaque structure outside of that subtree. The following patch moves the declaration from include/linux/sysfs.h to fs/sysfs/sysfs.h, making it clearer that nothing else in the kernel dereferences it. I have been running this patch for years. Please integrate and forward upstream if there are no objections. From: "Adam J. Richter" <adam@yggdrasil.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-02-16 13:35:25 +00:00
struct dentry * s_dentry;
struct iattr * s_iattr;
atomic_t s_event;
};
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
sysfs: slim down sysfs_dirent->s_active Make sysfs_dirent->s_active an atomic_t instead of rwsem. This reduces the size of sysfs_dirent from 136 to 104 on 64bit and from 76 to 60 on 32bit with lock debugging turned off. With lock debugging turned on the reduction is much larger. s_active starts at zero and each active reference increments s_active. Putting a reference decrements s_active. Deactivation subtracts SD_DEACTIVATED_BIAS which is currently INT_MIN and assumed to be small enough to make s_active negative. If s_active is negative, sysfs_get() no longer grants new references. Deactivation succeeds immediately if there is no active user; otherwise, it waits using a completion for the last put. Due to the removal of lockdep tricks, this change makes things less trickier in release_sysfs_dirent(). As all the complexity is contained in three s_active functions, I think it's more readable this way. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:18 +00:00
#define SD_DEACTIVATED_BIAS INT_MIN
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:16 +00:00
sysfs: restructure add/remove paths and fix inode update The original add/remove code had the following problems. * parent's timestamps are updated on dentry instantiation. this is incorrect with reclaimable files. * updating parent's timestamps isn't synchronized. * parent nlink update assumes the inode is accessible which won't be true once directory dentries are made reclaimable. This patch restructures add/remove paths to resolve the above problems. Add/removal are done in the following steps. 1. sysfs_addrm_start() : acquire locks including sysfs_mutex and other resources. 2-a. sysfs_add_one() : add new sd. linking the new sd into the children list is caller's responsibility. 2-b. sysfs_remove_one() : remove a sd. unlinking the sd from the children list is caller's responsibility. 3. sysfs_addrm_finish() : release all resources and clean up. Steps 2-a and/or 2-b can be repeated multiple times. Parent's inode is looked up during sysfs_addrm_start(). If available (always at the moment), it's pinned and nlink is updated as sd's are added and removed. Timestamps are updated during finish if any sd has been added or removed. If parent's inode is not available during start, sysfs_mutex ensures that parent inode is not created till add/remove is complete. All the complexity is contained inside the helper functions. Especially, dentry/inode handling is properly hidden from the rest of sysfs which now mostly operate on sysfs_dirents. As an added bonus, codes which use these helpers to add and remove sysfs_dirents are now more structured and simpler. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:24 +00:00
struct sysfs_addrm_cxt {
struct sysfs_dirent *parent_sd;
struct inode *parent_inode;
struct sysfs_dirent *removed;
int cnt;
};
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
extern struct vfsmount * sysfs_mount;
sysfs: make directory dentries and inodes reclaimable This patch makes dentries and inodes for sysfs directories reclaimable. * sysfs_notify() is modified to walk sysfs_dirent tree instead of dentry tree. * sysfs_update_file() and sysfs_chmod_file() use sysfs_get_dentry() to grab the victim dentry. * sysfs_rename_dir() and sysfs_move_dir() grab all dentries using sysfs_get_dentry() on startup. * Dentries for all shadowed directories are pinned in memory to serve as lookup start point. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:25 +00:00
extern struct sysfs_dirent sysfs_root;
[PATCH] slab: remove kmem_cache_t Replace all uses of kmem_cache_t with struct kmem_cache. The patch was generated using the following script: #!/bin/sh # # Replace one string by another in all the kernel sources. # set -e for file in `find * -name "*.c" -o -name "*.h"|xargs grep -l $1`; do quilt add $file sed -e "1,\$s/$1/$2/g" $file >/tmp/$$ mv /tmp/$$ $file quilt refresh done The script was run like this sh replace kmem_cache_t "struct kmem_cache" Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 04:33:20 +00:00
extern struct kmem_cache *sysfs_dir_cachep;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
sysfs: implement sysfs_get_dentry() Some sysfs operations require dentry and inode. sysfs_get_dentry() looks up and gets dentry for the specified sysfs_dirent. It finds the first ancestor with dentry attached and starts looking up dentries from there. Looking up from the nearest ancestor is necessary to support shadowed directories because we can't reliably lookup dentry for one of the shadows. Dentries for each shadow will be pinned in memory such that they can serve as the starting point for dentry lookup. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:25 +00:00
extern struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd);
sysfs: restructure add/remove paths and fix inode update The original add/remove code had the following problems. * parent's timestamps are updated on dentry instantiation. this is incorrect with reclaimable files. * updating parent's timestamps isn't synchronized. * parent nlink update assumes the inode is accessible which won't be true once directory dentries are made reclaimable. This patch restructures add/remove paths to resolve the above problems. Add/removal are done in the following steps. 1. sysfs_addrm_start() : acquire locks including sysfs_mutex and other resources. 2-a. sysfs_add_one() : add new sd. linking the new sd into the children list is caller's responsibility. 2-b. sysfs_remove_one() : remove a sd. unlinking the sd from the children list is caller's responsibility. 3. sysfs_addrm_finish() : release all resources and clean up. Steps 2-a and/or 2-b can be repeated multiple times. Parent's inode is looked up during sysfs_addrm_start(). If available (always at the moment), it's pinned and nlink is updated as sd's are added and removed. Timestamps are updated during finish if any sd has been added or removed. If parent's inode is not available during start, sysfs_mutex ensures that parent inode is not created till add/remove is complete. All the complexity is contained inside the helper functions. Especially, dentry/inode handling is properly hidden from the rest of sysfs which now mostly operate on sysfs_dirents. As an added bonus, codes which use these helpers to add and remove sysfs_dirents are now more structured and simpler. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:24 +00:00
extern void sysfs_link_sibling(struct sysfs_dirent *sd);
extern void sysfs_unlink_sibling(struct sysfs_dirent *sd);
sysfs: move s_active functions to fs/sysfs/dir.c These functions are about to receive more complexity and doesn't really need to be inlined in the first place. Move them from fs/sysfs/sysfs.h to fs/sysfs/dir.c. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:18 +00:00
extern struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
extern void sysfs_put_active(struct sysfs_dirent *sd);
extern struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd);
extern void sysfs_put_active_two(struct sysfs_dirent *sd);
sysfs: restructure add/remove paths and fix inode update The original add/remove code had the following problems. * parent's timestamps are updated on dentry instantiation. this is incorrect with reclaimable files. * updating parent's timestamps isn't synchronized. * parent nlink update assumes the inode is accessible which won't be true once directory dentries are made reclaimable. This patch restructures add/remove paths to resolve the above problems. Add/removal are done in the following steps. 1. sysfs_addrm_start() : acquire locks including sysfs_mutex and other resources. 2-a. sysfs_add_one() : add new sd. linking the new sd into the children list is caller's responsibility. 2-b. sysfs_remove_one() : remove a sd. unlinking the sd from the children list is caller's responsibility. 3. sysfs_addrm_finish() : release all resources and clean up. Steps 2-a and/or 2-b can be repeated multiple times. Parent's inode is looked up during sysfs_addrm_start(). If available (always at the moment), it's pinned and nlink is updated as sd's are added and removed. Timestamps are updated during finish if any sd has been added or removed. If parent's inode is not available during start, sysfs_mutex ensures that parent inode is not created till add/remove is complete. All the complexity is contained inside the helper functions. Especially, dentry/inode handling is properly hidden from the rest of sysfs which now mostly operate on sysfs_dirents. As an added bonus, codes which use these helpers to add and remove sysfs_dirents are now more structured and simpler. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:24 +00:00
extern void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
struct sysfs_dirent *parent_sd);
extern void sysfs_add_one(struct sysfs_addrm_cxt *acxt,
struct sysfs_dirent *sd);
extern void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
struct sysfs_dirent *sd);
extern int sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
sysfs: move s_active functions to fs/sysfs/dir.c These functions are about to receive more complexity and doesn't really need to be inlined in the first place. Move them from fs/sysfs/sysfs.h to fs/sysfs/dir.c. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:18 +00:00
sysfs: Shadow directory support The problem. When implementing a network namespace I need to be able to have multiple network devices with the same name. Currently this is a problem for /sys/class/net/*. What I want is a separate /sys/class/net directory in sysfs for each network namespace, and I want to name each of them /sys/class/net. I looked and the VFS actually allows that. All that is needed is for /sys/class/net to implement a follow link method to redirect lookups to the real directory you want. Implementing a follow link method that is sensitive to the current network namespace turns out to be 3 lines of code so it looks like a clean approach. Modifying sysfs so it doesn't get in my was is a bit trickier. I am calling the concept of multiple directories all at the same path in the filesystem shadow directories. With the directory entry really at that location the shadow master. The following patch modifies sysfs so it can handle a directory structure slightly different from the kobject tree so I can implement the shadow directories for handling /sys/class/net/. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-01-24 19:35:52 +00:00
extern void sysfs_delete_inode(struct inode *inode);
sysfs: reorganize sysfs_new_indoe() and sysfs_create() Reorganize/clean up sysfs_new_inode() and sysfs_create(). * sysfs_init_inode() is separated out from sysfs_new_inode() and is responsible for basic initialization. * sysfs_instantiate() replaces the last step of sysfs_create() and is responsible for dentry instantitaion. * type-specific initialization is moved out to the callers. * mode is specified only once when creating a sysfs_dirent. * spurious list_del_init(&sd->s_sibling) dropped from create_dir() This change is to * prepare for inode allocation fix. * separate alloc and init code for synchronization update. * make dentry/inode initialization more flexible for later changes. This patch doesn't introduce visible behavior change. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:17 +00:00
extern void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode);
sysfs: use iget_locked() instead of new_inode() After dentry is reclaimed, sysfs always used to allocate new dentry and inode if the file is accessed again. This causes problem with operations which only pin the inode. For example, if inotify watch is added to a sysfs file and the dentry for the file is reclaimed, the next update event creates new dentry and new inode making the inotify watch miss all the events from there on. This patch fixes it by using iget_locked() instead of new_inode(). sysfs_new_inode() is renamed to sysfs_get_inode() and inode is initialized iff the inode is newly allocated. sysfs_instantiate() is responsible for unlocking new inodes. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:17 +00:00
extern struct inode * sysfs_get_inode(struct sysfs_dirent *sd);
sysfs: reorganize sysfs_new_indoe() and sysfs_create() Reorganize/clean up sysfs_new_inode() and sysfs_create(). * sysfs_init_inode() is separated out from sysfs_new_inode() and is responsible for basic initialization. * sysfs_instantiate() replaces the last step of sysfs_create() and is responsible for dentry instantitaion. * type-specific initialization is moved out to the callers. * mode is specified only once when creating a sysfs_dirent. * spurious list_del_init(&sd->s_sibling) dropped from create_dir() This change is to * prepare for inode allocation fix. * separate alloc and init code for synchronization update. * make dentry/inode initialization more flexible for later changes. This patch doesn't introduce visible behavior change. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:17 +00:00
extern void sysfs_instantiate(struct dentry *dentry, struct inode *inode);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
sysfs: move release_sysfs_dirent() to dir.c There is no reason this function should be inlined and soon to follow sysfs object reference simplification will make it heavier. Move it to dir.c. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:13 +00:00
extern void release_sysfs_dirent(struct sysfs_dirent * sd);
sysfs: implement sysfs_find_dirent() and sysfs_get_dirent() Implement sysfs_find_dirent() and sysfs_get_dirent(). sysfs_dirent_exist() is replaced by sysfs_find_dirent(). These will be used to make directory entries reclamiable. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:22 +00:00
extern struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
const unsigned char *name);
extern struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
const unsigned char *name);
sysfs: make sysfs_dirent->s_element a union Make sd->s_element a union of sysfs_elem_{dir|symlink|attr|bin_attr} and rename it to s_elem. This is to achieve... * some level of type checking : changing symlink to point to sysfs_dirent instead of kobject is much safer and less painful now. * easier / standardized dereferencing * allow sysfs_elem_* to contain more than one entry Where possible, pointer is obtained by directly deferencing from sd instead of going through other entities. This reduces dependencies to dentry, inode and kobject. to_attr() and to_bin_attr() are unused now and removed. This is in preparation of object reference simplification. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:15 +00:00
extern struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode,
int type);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
sysfs: make kobj point to sysfs_dirent instead of dentry As kobj sysfs dentries and inodes are gonna be made reclaimable, dentry can't be used as naming token for sysfs file/directory, replace kobj->dentry with kobj->sd. The only external interface change is shadow directory handling. All other changes are contained in kobj and sysfs. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:22 +00:00
extern int sysfs_add_file(struct sysfs_dirent *dir_sd,
const struct attribute *attr, int type);
extern int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name);
[PATCH] sysfs: Allow sysfs attribute files to be pollable It works like this: Open the file Read all the contents. Call poll requesting POLLERR or POLLPRI (so select/exceptfds works) When poll returns, close the file and go to top of loop. or lseek to start of file and go back to the 'read'. Events are signaled by an object manager calling sysfs_notify(kobj, dir, attr); If the dir is non-NULL, it is used to find a subdirectory which contains the attribute (presumably created by sysfs_create_group). This has a cost of one int per attribute, one wait_queuehead per kobject, one int per open file. The name "sysfs_notify" may be confused with the inotify functionality. Maybe it would be nice to support inotify for sysfs attributes as well? This patch also uses sysfs_notify to allow /sys/block/md*/md/sync_action to be pollable Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-03-20 06:53:53 +00:00
extern struct sysfs_dirent *sysfs_find(struct sysfs_dirent *dir, const char * name);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
sysfs: make kobj point to sysfs_dirent instead of dentry As kobj sysfs dentries and inodes are gonna be made reclaimable, dentry can't be used as naming token for sysfs file/directory, replace kobj->dentry with kobj->sd. The only external interface change is shadow directory handling. All other changes are contained in kobj and sysfs. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:22 +00:00
extern int sysfs_create_subdir(struct kobject *kobj, const char *name,
struct sysfs_dirent **p_sd);
extern void sysfs_remove_subdir(struct sysfs_dirent *sd);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
[PATCH] sysfs-iattr: add sysfs_setattr o This adds ->i_op->setattr VFS method for sysfs inodes. The changed attribues are saved in the persistent sysfs_dirent structure as a pointer to struct iattr. The struct iattr is allocated only for those sysfs_dirent's for which default attributes are getting changed. Thanks to Jon Smirl for this suggestion. Signed-off-by: Maneesh Soni <maneesh@in.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2005-05-31 05:09:14 +00:00
extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
sysfs: consolidate sysfs spinlocks Replace sysfs_lock and kobj_sysfs_assoc_lock with sysfs_assoc_lock. sysfs_lock was originally to be used to protect sysfs_dirent tree but mutex seems better choice, so there is no reason to keep sysfs_lock separate. Merge the two spinlocks into one. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:23 +00:00
extern spinlock_t sysfs_assoc_lock;
sysfs: use sysfs_mutex to protect the sysfs_dirent tree As kobj sysfs dentries and inodes are gonna be made reclaimable, i_mutex can't be used to protect sysfs_dirent tree. Use sysfs_mutex globally instead. As the whole tree is protected with sysfs_mutex, there is no reason to keep sysfs_rename_sem. Drop it. While at it, add docbook comments to functions which require sysfs_mutex locking. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:23 +00:00
extern struct mutex sysfs_mutex;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
extern struct super_block * sysfs_sb;
[PATCH] Make most file operations structs in fs/ const This is a conversion to make the various file_operations structs in fs/ const. Basically a regexp job, with a few manual fixups The goal is both to increase correctness (harder to accidentally write to shared datastructures) and reducing the false sharing of cachelines with things that get dirty in .data (while .rodata is nicely read only and thus cache clean) Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-28 09:56:42 +00:00
extern const struct file_operations sysfs_dir_operations;
extern const struct file_operations sysfs_file_operations;
extern const struct file_operations bin_fops;
[PATCH] mark struct inode_operations const 3 Many struct inode_operations in the kernel can be "const". Marking them const moves these to the .rodata section, which avoids false sharing with potential dirty data. In addition it'll catch accidental writes at compile time to these shared resources. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 08:55:40 +00:00
extern const struct inode_operations sysfs_dir_inode_operations;
extern const struct inode_operations sysfs_symlink_inode_operations;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
sysfs: rename sysfs_dirent->s_type to s_flags and make room for flags Rename sysfs_dirent->s_type to s_flags, pack type into lower eight bits and reserve the rest for flags. sysfs_type() can used to access the type. All existing sd->s_type accesses are converted to use sysfs_type(). While at it, type test is changed to equality test instead of bit-and test where appropriate. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 19:27:21 +00:00
static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
{
return sd->s_flags & SYSFS_TYPE_MASK;
}
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:16 +00:00
static inline struct sysfs_dirent * sysfs_get(struct sysfs_dirent * sd)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:16 +00:00
if (sd) {
WARN_ON(!atomic_read(&sd->s_count));
atomic_inc(&sd->s_count);
}
return sd;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
}
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:16 +00:00
static inline void sysfs_put(struct sysfs_dirent * sd)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:16 +00:00
if (sd && atomic_dec_and_test(&sd->s_count))
release_sysfs_dirent(sd);
}
sysfs: reimplement symlink using sysfs_dirent tree sysfs symlink is implemented by referencing dentry and kobject from sysfs_dirent - symlink entry references kobject, dentry is used to walk the tree. This complicates object lifetimes rules and is dangerous - for example, there is no way to tell to which module the target of a symlink belongs and referencing that kobject can make it linger after the module is gone. This patch reimplements symlink using only sysfs_dirent tree. sd for a symlink points and holds reference to the target sysfs_dirent and all walking is done using sysfs_dirent tree. Simpler and safer. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 18:45:15 +00:00
sysfs: Shadow directory support The problem. When implementing a network namespace I need to be able to have multiple network devices with the same name. Currently this is a problem for /sys/class/net/*. What I want is a separate /sys/class/net directory in sysfs for each network namespace, and I want to name each of them /sys/class/net. I looked and the VFS actually allows that. All that is needed is for /sys/class/net to implement a follow link method to redirect lookups to the real directory you want. Implementing a follow link method that is sensitive to the current network namespace turns out to be 3 lines of code so it looks like a clean approach. Modifying sysfs so it doesn't get in my was is a bit trickier. I am calling the concept of multiple directories all at the same path in the filesystem shadow directories. With the directory entry really at that location the shadow master. The following patch modifies sysfs so it can handle a directory structure slightly different from the kobject tree so I can implement the shadow directories for handling /sys/class/net/. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-01-24 19:35:52 +00:00
static inline int sysfs_is_shadowed_inode(struct inode *inode)
{
return S_ISDIR(inode->i_mode) && inode->i_op->follow_link;
}
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